How to Make Your Split System Air Conditioner Smart (Without Replacing It)

Most smart home advice about climate control is written for American central heating and cooling with a single wall thermostat. That is not how most Australian homes work.

We mostly run reverse-cycle split systems — one or more wall-mounted indoor units, each with its own infrared remote that lives somewhere between the couch cushions — or ducted systems with a wall controller. The advice for one does not transfer to the other, which is why so much of what you read online is unhelpful here.

The good news: you rarely need to replace a working split system to get app control, scheduling and voice commands. Here is what actually works, what each approach can and cannot do, and when you need a professional.

Why bother

Heating and cooling is a big part of the power bill. The federal government's energy advice site says that, depending on climate zone, it can account for 20% to 50% of the energy used in Australian homes. It also says each extra degree of heating in winter or cooling in summer increases energy use by between 5% and 10%. Automation will not change the physics, but it does make the money-saving habits happen without anyone having to remember them — above all, not running the aircon in an empty house.

Option 1: a smart infrared controller

Best for: almost anyone with a split system and an infrared remote, including renters.

How it works

Your remote is not a thermostat. When you press "22 degrees, cool, fan auto", it transmits the entire settings state as one infrared burst. The indoor unit receives it, acts on it and beeps. It has no way to report back.

A smart IR controller (also called an IR bridge or blaster) sits in the room and replicates that burst on demand. You tell the app or your voice assistant "22, cool, auto", the controller fires the matching IR code across the room, and the split system obeys exactly as if you had used the remote.

Advantages: it works with most units regardless of brand or age, needs no wiring and no installer, and nothing inside the air conditioner is touched. It plugs into a USB power supply and sits on a shelf, so it generally suits renters too. If you want to stick it to a wall, check your lease or your state's tenancy authority before using adhesive on the property.

The one-way problem

Infrared is one-way. The controller sends a command and assumes it worked, so the app is guessing at the current state. The classic failure: someone turns the aircon off with the physical remote, the smart home still believes it is on, and your automations start making decisions based on a false picture. Or an "off" command goes to a unit that was already off and toggles it on.

Better controllers work around this in two ways. The first is a built-in temperature sensor, so the app knows the real room conditions. The second is an IR receiver that watches for presses on the original remote and updates its own state to match. That second feature is the biggest practical difference between a basic blaster and a better controller, and it is worth having in a busy household.

Budget blaster or sensor-led controller

Budget Tuya / Smart Life IR blasters, sold widely on Amazon AU, eBay AU and Kogan, do the core job. You pick your aircon brand from a code library, test code sets until the unit responds, and link the app to Google Home or Alexa. Expect basic scheduling, cloud dependence and little or no state feedback.

Sensor-led controllers behave more like a genuine thermostat. The Sensibo Air is the best-known example. Sensibo lists a temperature and humidity sensor, a "universal IR receiver", geofencing that switches on before you arrive and off when the last person leaves, and support for Alexa, Google Assistant, Apple HomeKit and SmartThings. A budget blaster turns your split system into a remote you can talk to; a sensor-led controller turns it into something closer to a connected climate device. Both are legitimate — buy the one that matches what you actually want. If location-based triggers appeal, see our guide to setting up air con geofencing and the trade-offs to keep in mind.

Where to put an IR controller

IR is line of sight — not "roughly in the direction of". The controller needs a clear path to the receiver window on the indoor unit.

• Stay within the stated range. Sensibo, for example, specifies line of sight to the AC unit up to 6 metres; check the figure for your model.
• Bounce is real but unreliable. Signals can reflect off pale walls and ceilings, so an angled spot sometimes works. Test before you commit to double-sided tape.
• Avoid strong light on the sensor window. Bright sunlight can interfere with infrared reception.
• Keep it near power. The Sensibo Air runs from a 5V micro USB adaptor, so a USB plug in a nearby power point is all it needs — no electrical work.
• One controller per room. IR does not go through walls. If the unit sits above a doorway on the far side of an L-shaped room, you may need a second controller rather than fighting the physics.

Setting up an IR controller

1. Note your aircon brand and remote model. The model number on the remote is often what code libraries are organised by.
2. Check your Wi-Fi band. Many controllers, including the Sensibo Air, connect on 2.4GHz only. If your router combines 2.4GHz and 5GHz under one network name and pairing fails, check the router's settings for a way to separate them during setup.
3. Pair the controller using the vendor app.
4. Run the code-matching wizard with the controller pointed at the indoor unit. Some brands match first try; older or less common units can take several attempts.
5. Test every function you care about — cool, heat, dry, fan speed, swing and exact temperature. A code set can get power and temperature right but map swing incorrectly.
6. Link your voice assistant by connecting the vendor's account in the Google Home or Alexa app, and assign the device to a room.
7. Use a name you would actually say. "Lounge aircon" beats a default device ID every time.

Automations worth setting up

• Off when everyone leaves. Geofencing or an "away" routine. This is the single biggest saving, because leaving the aircon on all day is a very common and expensive mistake.
• Pre-conditioning. Start heating or cooling a short time before someone usually gets home, rather than running all afternoon.
• Open-door shutoff. Pair with a contact sensor so the unit stops when a door or window is left open.
• Room-by-room logic. Cool bedrooms in the evening and the living area during the day, rather than everything at once.
• Solar and tariff awareness. If you monitor your solar system, run harder during surplus and ease off during peak tariff periods.
• Overnight profiles. Step the setpoint gently through the night rather than holding one temperature.

Making it reliable

Add a room sensor. The aircon's own sensor is in the indoor unit, usually high on the wall where the air is warmest. A separate sensor at seated height in the middle of the room gives a number that reflects how the room actually feels — automate against that. With a basic blaster, a temperature sensor or a power monitor on the aircon also lets the system infer whether the unit is really running.

Add humidity, especially in humid climates. Twenty-six degrees at 45% humidity and at 80% humidity are very different experiences, and humidity-aware automation is more comfortable than temperature alone.

Start small. Begin with two rules — off when everyone leaves, pre-condition before someone arrives. Those capture most of the value. Add complexity once you trust it.

Give people a manual override. If the automation fights the occupants, the occupants win and the automation gets deleted. Make sure using the remote does something sensible, and that automations back off for a while after manual intervention.

Home Assistant and local control

Home Assistant's Sensibo integration is part of core and exposes a climate entity, but it is cloud polling rather than local. Tuya-based blasters are less straightforward: the official Tuya integration is cloud-based and does not support the remote platform, so IR blasters may not appear as clean climate devices. If local-only control is a hard requirement, check current community reports for your exact model before buying.

What an IR controller won't do, and when to call a professional

An IR controller cannot read the compressor, error codes, filter status or the unit's own energy use. It also cannot run ducted systems that use a wall controller, or units with a hard-wired remote. For those, look at the manufacturer's Wi-Fi adaptor or a third-party wired controller.

Anything that involves opening the indoor unit or connecting to its control board is a job for the installer the manufacturer specifies, and doing it yourself may affect your warranty. Electrical work is regulated by each state and territory. Queensland's Electrical Safety Office, for instance, says appliances that need to be hard-wired "must be connected by a licensed electrician". Rules differ between states, so check with your installer, the manufacturer and your state's electrical safety regulator before anyone opens the unit.

A note on running costs

Smart control makes an air conditioner more convenient, and it can make it cheaper — but the savings come from not running it when nobody needs it, not from the gadget itself. The highest-value automations are the boring ones: off when the house is empty, no cooling rooms nobody is in, and sensible setpoints. Set up the geofence and schedule properly and the benefit is real. Use it only as a voice remote and you have bought convenience, which is fine — just go in with clear eyes.

For the tariff side, our guide to whether smart plugs actually save money covers how load shifting works on Australian tariffs.